Pump control system



Dec. 2, 1947. R. B. DRESCHER ET AL 2,431,995

PUMP CONTROL SYSTEM Filed Sept. 25, 1944 2 Sheets-Sheet 1 Dec. 2, 1947.

R. B. DRESCHER El AL PUMP CONTROL SYSTEM Filed Sept. 25, 1944 2 Sheets-Sheet 2- 64 GOVERNOR (66 6'2 .9'0

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za-=-- 5.9- LL72 Patented Dec. 2, 1947 UNITED STATES PATENT OFFICE PUMP CONTROL SYSTEM Rowland B. Drescher and Alfred C. Wenzel, Chicago, Ill., assignors to Republic Flow Meters Company, Chicago, Ill., a corporation of Illinois Application September 25, 1944, Serial No. 555,740

14 Claims. (01. 103-11) '1 2 This invention relates to a pump control sysand discharges into a main discharge conduit l2 tem and more particularly to a system for conwhich may lead to any desired point of use. The trolling the operation of pumps, compressors and speed of the turbine may be regulated in any dethe like to prevent back surges or so-called sired manner, as for example, by a governor l3, P D and a blow-oil? valve I4 is connected to the con- In the operation of pumps and compressors duit l2 and discharges to atmosphere at any de-v and particularly of centrifugal pumps and axial sired point. The blow-off valve is operated by a flow compressors, if the flow is throttled to an regulator indicated generally at I5which will open amount sufficient to raise the pressure above a the valve M to varying degrees in accordance with critical value for any given pump speed back pressure supplied thereto thru a pipe IS. The surges from the discharge line into the pump regulator I5 may be of any desired construction occur resulting in a so-called pumping condition such, for example, as that shown in the patent and setting up vibrations and excessive strains to Rosenberger No. 2220,176. on the machinery. To eliminate this condition In accordance with the present invention, the it has been proposed to provide blow off valves blow-off valve is controlled in response to variaconnected to the pump discharge and adapted to tions in 'the discharge pressure and in the flow be opened when the flow thru the pump falls thru the pump. For this purpose a pitot tube below a predetermined minimum. l I is arranged in the discharge conduit I2 an- It is one of the objects of the present invention terior to the connection to the blow off valve 14. to provide a pump control system in which the Tube pipes l8 and I9 are connected to the pitot blow-off valve is controlled in accordance with tube, the pipe l8 carrying the upstream pressure the relationship between discharge pressure and and the pipe l9 carrying the downstream presflow to prevent the establishment of a pumping sure. The pipes l8 and I9 are connected thru condition. condensate collectors 2| to the opposite sides of It is another object of the invention to proaflexible diaphragm 22 which is connected to one vide a pump control system in which both the end of a balance beam 23 pivoted at 24 and formblcw ofi valve and the pump speed are controlled ing a part of a regulator. The diaphragm 22, in accordance with functions of the discharge therefore, exerts on the beam 23 a force proporpressure and the flow thru the pump. ftional to the differential pressure across the pitot Still another object is to provide a pump contube tending to tilt the beam clockwise.

trol system in which the efiect of the discharge The force of the diaphragm 22 is balanced by pressure on the blow of! valve is automatically a diaphragm 25 supplied on its upper side with varied to produce any desired control operation. loading pressure thru a loading line 26 for tend- In one preferred embodiment the discharge presing to tilt the beam counter-clockwise. The beam sure operates thr a cam mechanism which may is connected thru a link 21 to an adjustable bleed be shaped to produce the desired control of the valve 28 to control the bleed valve in accordblow ofi valve. ance with the balance between a function of the A still further object is to provide a pump conflow thru the pump and the loading pressure. trol system in which the pump speed is controlled While the regulator has been shown diagramby the balance between an adjustable loading matically with the beam 23 connected directly to pressure and the pump discharge pressure and the valve 28, it will be understood that any dethe blow ofi valve is controlled in accordance sired type of regulator including power relay with the balance between the loading pressure mechanism, could be used to operate the valve. and a function of the flow thru the pump. Fluid is suppliedto the valve 28 from any de- The above and other objects and advantages sired source thru a line 3| having a restriction of the invention will be more readily apparent 32 therein so that the extent of opening of the from the following description when read in convalve 28 determines the pressure in the line 3| nection with the accompanying drawing, in beyond the restriction. Thus, the valve 28 prowhichduces a. regulated loading pressure in the line Figures 1 and 2 are diagrammatic views of 3| which may be connected directly to the govalternative pump control systems embodying the ernor l3 and to the regulator l5 thru the pipe invention. I6 as shown.

In the system shown in Figure 1 an axial flow The loading pressure supplied to the ditype pump or compressor I0 is driven by any aphragm 25'thru the pipe 26 is produced in acdesired type of power means such as a turbine ll ,cordance with the discharge pressure in the pipe 12. For this purpose the pipe [8 is connected to a chamber 33 closed on one side by av flexible bellows 34. The pressure in the chamber will move the bellows against its natural resilience but if desired, an additional spring could be provided to urge the bellows to expand against the pressure in the chamber. The bellows is connected to one end of a lever 35 fixedly pivoted at 36 and carrying at its opposite end a cam follower engageable with an elongated cam 31. The cam 31 is pivoted at 38 on .a bar 39 which is supported by a link 4| and by a hollow discharge tube 42. The tube 42 is connected to and opens thru the end of a bellow 43 closing one end of a pressure chamber 44. An extension on the cam is movable toward and away from the outer end of the tube 42 variably to restrict the discharge therethrough, thereby to control the pressure in the chamber 44. A spring 45 is preferably provided urging the lower end of the lever 31 toward the tube 42.

The chamber 44 is supplied with fluid such as air under pressure thru a pipe 46 under the control of a pressure regulator 41. An orifice 48 is provided in the supply line so that variable restriction of the discharge end of the tube 42 will regulate the pressure in the chamber 44. The pipe 26 i connected to the'chamber 44 to conduct regulated pressure therefrom to the diaphragm 25.

In operation the regulator 23 will control the valve 28 to produce a regulated loading pressure in the line l'6 which acts on the regulator l5 to control opening of the blow-off valve. If the rate of flow thru the compressor is high enough relative to the pressure existing in the discharge conduit so that no pumping will occur, the blowoff valve will be closed. At this time, the turbine will operate at a speed determined by the setting of the governor or other control to maintain the desired pressure and rate of flow in the discharge conduit l2. If the demand should decrease to a point where pressure in the discharge conduit increases relative to the rate of flow to a suflicient degree to cause pumping, the control system will operate to open the blow-off valve. When this condition occurs the pressure increase is transmitted thru the line l8 to the chamber 33 to rock the lever 35 counter-clockwise moving the follower away from the cam 31. The spring 45 may then move the lower end of the cam lever toward the discharge tube 42 to increase the pres sure ighe chamber 44. This will move the bellows 3 to the left moving the discharge rod and the bar 39 to the left until the cam 31 again engages the follower and the system arrives at a balanced condition with an increased pressure in the chamber 44. This increased pressure is transmitted thru the pipe 26 to the diaphragm to rock the beam 23 counter-clockwise and reset the valve 28. It will be understood that the valve 28 may be either opened or closed a desired, in accordance with the setting of the governor and of the regulator l5. Assuming for example, that the valve 28 is opened when the lever 23. rocks counter-clockwise, the pressure in line l6 will be decreased to decrease the loading on the regulator l5 to cause opening of the blow-off valve l4. When the rate of flow thru the pump again reaches a value relative to the pressure such that pumping wil1 not occur, the valve M will be closed. This action is produced by the differential pressure acting on the diaphragm 22 in response to flow thru the discharge conduit balancing the loading pressure on the diaphragm 25.

By shaping the cam 31 any desired control can be obtained so that the system wil1 operate at all times with a predetermined relationship between discharge pressure and total flow thru the pump. Thus the system can easily be accommodated to various type of pumps and to various operating conditions.

The connection of line IE to the governor l3 provides a safety control to prevent racing of the turbine. If the turbine'speed should increase above a predetermined maximum value the governor l3 will vent the line I6 to reduce the pressure therein. This will cause the regulator l5 to open the valve [4 to increase the flow thru the compressor, thereby increasing the load on the turbine to limit its speed.

In the system shown in Figure 2, a pump 56 is driven by a turbine 5| which is controlled by a governor 52. The pump is supplied with air thru an inlet conduit 53 and discharges air under pressure thru a discharge conduit 54 which is provided with a blow-off valve 55.

In this system the desired discharge pressure is adapted to be set manually thru a manually controlled pressure regulator 56 which supplies loading pressure to a pipe 51. For controlling the turbine speed the pipe 51 is connected to a diaphragm 58 acting on one end of a weigh beam 59. The weigh beam is balanced by a diaphragm 6! connected thru a pipe 62 to the discharge conduit 54. Balance of the weigh beam is therefore determined by the balance between the loadin pressure and the pump discharge pressure.

The weigh beam 59 controls a valve member '63 which moves toward and away from a nozzle 64 supplied with fluid such as air thru a restriction 65. Pressure in the nozzle 64 is supplied to the governor thru a pipe 66 to load the governor thereby to control the speed of the turbine.

The loading pressure in pipe 51 is also utilized to control opening of the blow off valve 55 and for this purpose the pipe 51 is connected to a diaphragm 61 acting on one end of a weigh beam 68 forming part of a regulator having a power unit 69. The weigh beam is balanced by a diaphragm H connected on its opposite sides thru pipes "to the inlet pipe 53 on the opposite sides of a restriction 13 therein. As the weigh beam moves in response to unbalance of the diaphragms it causes the power unit to move an arm I4 vertically. The arm 74 is connected thru a link 15 to a blow-off valve 55 to open it.

In operation of this system the turbine and pump speeds are regulated thru the governor in accordance with the balance between the loading pressure and the pump discharge pressure. In the event the discharge pressure is below the loading pressure, the valve member 63 will move toward the nozzle 64 to increase the loading pressure supplied to the governor thru the line 66. The governor will, therefore, be additionally loaded to cause the turbine speed to increase tending to bring the pump discharge pressure up to the desired value.

In the event the volume of flow thru the pump falls below the critical value at which pumping will occur, the differential across the diaphragm II will drop causing the beam 68 to turn clockwise. This will operate the power unit 69 to move the arm 14 in a direction to open the valve 55 to establish the desired minimum flow thru the pump. Since the differential across the diaphragm II is a square function of the flow thru the orifice 13 th relationship between the loading pressure and the flow will be a square relationship. This is desirable since the pump operating curves do not increase linearly with the pump speed so that in all ranges of the operation the regulator will function to maintain a safe minimum flow thru the pump.

While two embodiments of the invention have been shown and described in detail herein, it will be understood that these are illustrative only and are not intended as definition of the scope of the invention, reference being had for this purpose to the appended claims.

What is claimed is:

-1. A control system for a pump having a discharge conduit with a blow-oil valve therein comprising a regulator for controlling the blowolf valve, control means for controlling the regulator, means responsive to the rate of flow thru the discharge conduit to operate the control means, and means responsive to the pressure in the discharge conduit to modify operation of the control means by the flow responsive means.

2. A control system for a pump having a discharge conduit with a blow-off valve therein comprising a regulator responsive to the balance between the pressure in the discharge conduit and of the rate of flow thru the pump, and means operated by the regulator to control the blow-cit valve.

3. A control system for a pump having a discharge conduit with a blow-off valve therein comprising a governor for controlling the speed of the pump, a regulator for controlling the blowoff valve, means responsive to the pressure in the discharge conduit variably to load the governor thereby to control the speed of the pump, and means responsive to the rate of flow through the pump to control the regulator.

4. A control system for a pump having a discharge conduit with a blow off valve therein comprising a governor for controlling the speed of the pump, a regulator for controlling the blow off valve, a regulator responsive to the pressure in the discharge conduit to create a loading pressure, the governor being connected to the last named regulator to control the speed of the pump in response to the loading pressure, and means for operating the first named regulator in response to the rate of flow thru the pump.

5. A control system for a pump having a discharge conduit with a blow oil valve therein comprising a regulator responsive to the balance between the pressure in the discharge conduit and the rate of flow thru the pump, means operated by the regulator to control the blow-off valve, and means operated by th regulator to control the speed of the pump. a

6. A control system for a pump having a dis-- charge conduit with a blow off valve therein comprising a regulator including balance means, means responsive to the rate of flow thru the pump to urge the balance means in one direction, a diaphragm acting on the balance means to urge it in the opposite direction, means responsive to the pressure in the discharge conduit to supply a variable loading pressure to the diaphragm, and means controlled by the regulator to operate the blow-off valve.

7. A control system for a pump having a discharge conduit with a blow off valve therein comprising a regulator including balance means, means responsive to the rate of flow thru the pump to urge the balance means in one direction, a diaphragm acting on the balance means to urge it in the opposite direction, means to supply a, loading pressure to the diaphragm, means controlled in response to the pressure in the discharge conduit to vary the loading pressure, and means controlled by the regulator to operate the blow-ofi valve.

8. A control system for a pump having a discharge conduit with a blow off valve therein comprising a regulator including balance means, means responsive to the rate of flow thru the pump to urge the balance means in one direction, a diaphragm acting on the balance means to urge it,in the opposite direction, a loading line connected to the diaphragm to supply loading pressure thereto, control means to vary the loading pressure, a pressure responsive member movable in response to the pressure in the discharge conduit, means including a cam connecting the pressure responsive member to the control means, and means controlled by the regulator to operate the blow-off valve.

9. A control system for a pump having a discharge conduit with a blow-off valve therein comprising a regulator including balance means, means responsive to the rate of flow thru the pump to urge the balance means in one direction, a diaphragm acting on the balance means to urge it in the opposite direction, a loading line connected to the diaphragm to supply loading pressure thereto, control means to vary the loading pressure, a pressure responsive member movable in response to pressure in the discharge conduit, means including a cam connecting the pressure responsive member to the control means, means controlled by the regulator to operate the blow-off valve, and means controlled by the speed of the pump to control operation of the blow-off valve.

10. A control system for a pump having a discharge conduit with a, blow-off valve therein comprising a regulator including balance means, means responsive to the rate of flow thru the pump to urge the balance means in one direc-- tion, a diaphragm acting on the .balance means to urge it in the opposite direction, a loading line connected to the diaphragm to supply loading pressure thereto, a bleed valve connected to the line including two relatively movable elements to control the loading pressure, an element responsive to the loading pressure connected to one of the valve elements to move it, a pressure responsive member movablein response to the pressure in the discharge conduit, cam means connecting the pressure responsive member to the other valve element, and means controlled by the regulator to operate the blow-off valve.

'11. A control system for a pump having a discharge conduit With a blow-off valve therein comprising a regulator including balance means, means responsive to the rate of flow thru the pump to urge the balance means in one direction, a diaphragm acting on the balance means to urge it in the opposite direction, a loading line connected to the diaphragm to supply loading pressure thereto, a bleed valve connected to the line including two relatively movable elements to control the loading pressure, an element responsive to the loading pressure connected to one of the valve elements to move it, a pressure responsive member movable in response to the pressure in the discharge conduit, cam means connecting the pressure responsive member to the other valve element, means operated by the regulator to produce a variable loading pressure,

76 means responsive to the last named loading pres- 7 sure to control the blow-off valve, and means responsive to the speed of the pump to vary the last named loading pressure.

12. A control system for a pump having a discharge conduit with a blow-01f valve therein comprising means to produce a regulated loading pressure, a regulator including balance means, means responsive to the loading pressure to urge the balance means in one direction, means responsive to the flow thru the pump to urge the balance means in the other direction, and means controlled by the balance means to operate the blow-off valve.

13. A control system for a pump having a discharge conduit with a blow-off valve therein comprising means to produce a regulated loading pressure, a regulator including balance means, means responsive to the loading pressure to urge the balance means in one direction, means responsive to the flow thru the pump to urge the balance means in the other direction, and means controlled by the balance means to operate the blow-off valve, a second regulator controlled by the balance between the loading pressure and the pressure in the discharge conduit, and means controlled by the second regulator to control the speed of the pump.

14. A control system for a pump having a discharge conduit with a blow-ofi valve therein comprising means to produce a regulated loading pressure, a regulator including balance means, means responsive to the loading pressure to urge the balance means in one direction, means responsive to the flow thru the pump to urge the balance means in the other direction, means controlled by the balance means to operate the blowoff valve, a second regulator controlled by the balance between the loading pressure and the pressure in the discharge conduit, means controlled by the second regulator to produce a second loading pressure, and means responsive to the second loading pressure to control the speed of the pump.

ROWLAND B. DRESCHER.

ALFRED C. WENZEL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,154,959 Banner Sept. 28, 1915 1,198,162 -Smoot Sept. 12, 1916 1,383,258 Hoffman June 28, 1921 1,874,136 Standerwick Aug. 30, 1932 1,953,827 Hillier Apr, 3, 1934 

